Smallpox is the poster child for disease eradication. That's because it's the only true success story thus far. For thousands of years, the disease swept around the globe causing countless outbreaks, killing as many as 30 percent of its victims and leaving most of its survivors scarred and blind. It killed the poor and the wealthy alike. In fact, Queen Mary II of England, Tsar Peter II of Russia and King Louis XV of France all died from smallpox. Yet all this changed in 1796 when Edward Jenner, an English scientist, created the world's first vaccine -- the smallpox vaccine -- using the cowpox virus, a similar, but less lethal disease. After a worldwide eradication effort lasting more than 100 years, the disease finally infected its last victim in 1977.